In CT imaging systems, pre-patient filters and collimators are used to shape an x-ray beam so that a fan-shaped x-ray beam lies within the X-Y plane, or the imaging plane, before its transmission through a patient. These pre-patient filters are generally used to shape the intensity of the x-ray beam in the X-direction, and are commonly enclosed in a housing (i.e., collimator) that determines the width of the x-ray beam in the Z-direction. The filtered and collimated x-ray beam is attenuated by the object being imaged (i.e., the patient having the CT scan performed on them), and the x-rays are then detected by an array of radiation detectors. Often times, the x-rays pass through a post-patient collimator prior to being detected by the array of radiation detectors. These post-patient collimators generally comprise a number of various parts that can be very difficult to accurately align and assemble.
The pre-patient collimators often generate significant scattered radiation that subjects the patient to x-ray dose that is not useful in the CT imaging process. Such scatter is becoming an increasing problem as CT manufacturers open up the fan-shaped x-ray beam more and more in the Z-direction to accommodate detectors with more slices and coverage in the Z-direction, thereby increasing the need for better pre-patient and post-patient collimator designs. As CT systems are becoming increasingly dose sensitive, it would be desirable to have systems and methods for making pre-patient filter/collimator assemblies that minimize the scattered radiation created therein and exiting therefrom so as to lower the x-ray dose the patient is exposed to.
The post-patient collimators are generally complicated structures comprising combs, rails, plates and wires. Currently, each comb must be attached to a rail, each plate must be individually inserted into appropriate slots in the combs and be attached thereto, and then wires must be individually strung and attached to the appropriate slots on each plate. This is a very time consuming, labor-intensive process, often requiring reworking if the components are not properly aligned. Therefore, it would be desirable to have systems and methods for making post-patient collimators in an easier, more efficient, and more economical manner than currently possible.
Filters used with such collimators could also be better designed to minimize the scattered radiation created therein and exiting therefrom so as to help further lower the x-ray dose the patient is exposed to.
It would be desirable to have collimators, both pre-patient and post-patient, that lower the x-ray dose the patient is exposed to by minimizing the scattered radiation created therein or exiting therefrom. It would be further desirable to have such collimators that can be more easily, more accurately, and more efficiently made than currently possible. It would also be desirable to have filters that minimize the scattered radiation created therein and exiting therefrom, for use in combination with such collimators, so as to help further reduce the x-ray dose the patient is exposed to. It would be still further desirable to have such filters and/or collimators be made of one or more cast pieces of a suitable high density, high atomic number material. Finally, it would be desirable to have such collimators to allow improved x-ray dose efficiency. Many other needs will also be met by this invention, as will become more apparent throughout the remainder of the disclosure that follows.